Defense Secretary Jim Mattis spoke to reporters after meetings today in Riyadh, Saudi Arabia, touching on the kingdom’s leading role in regional security as well as on countering Iranian influence and negotiating peace in Yemen.

The discussions were candid and highly productive, he said, calling Saudi Arabia “one of our best counterterrorism partners.”

“What was really obvious to me today was the regional leadership role of the Saudis, and how they’re helping across the region,” Mattis said, including supporting Jordan in caring for refugees who have fled the fighting in Syria, and also providing energy supplies and other support to Egypt “as they work through some really tough financial times.”

“It’s very clear that Saudi Arabia is stepping up to its regional leadership role … at a key time in terms of trying to restore stability in this key region in the world,” he said.

Iran’s Influence Stretches to Lebanon, Syria, Yemen

In response to a reporter’s question the secretary said that the United States remains watchful in assessing Iran’s regional influence, including its support to Hezbollah in Lebanon and its “thousands of fighters” in Syria helping to keep President Bashar Assad in power.

“Everywhere you look, if there’s trouble in the region, you find Iran,” Mattis said. “ … The nations in the region and others elsewhere are trying to checkmate Iran and the amount of disruption, the amount of instability they can cause.”

Turning to Yemen, the secretary said the goal is to push the conflict there into United Nations-brokered negotiations “to ensure that it ends as soon as possible.”

In January 2015, Houthi militiamen representing the Yemen’s Zaidi sect, an offshoot of Shia Islam, took over the capital of Sanaa.

In March 2015, a Saudi-led coalition began launching airstrikes against the Houthis. According to published reports, Jihadist militants from al-Qaida in the Arabian Peninsula and other affiliates of the Islamic State of Iraq and Syria have meanwhile seized territory in the south of Yemen and mounted attacks in Aden, still under government control. The U.S. military has conducted a reported 70 airstrikes targeting the organization as of April 3.

Iran has backed the Houthi rebels with weapons, Mattis said, adding that some shipments have been intercepted by the French, Australian and U.S. navies.

“We will make progress on this, the international community will make progress on it,” Mattis said. “We will have to overcome Iran’s efforts to destabilize yet another country and create another militia in their image of Lebanese Hezbollah.”

The secretary said “the right path” for Yemen is to “get this in front of a negotiated peace [process] by the United Nations.”